1. Field of the Invention
The present invention relates to an image forming apparatus such as an electrophotographic printer, copying machine or facsimile, and more particularly to an image forming apparatus incorporating a unit for cooling an image formation portion.
2. Description of the Related Art
In an electrophotographic image forming apparatus, as its functions such as double-sided printing are enhanced and the resolution in image quality is increased, the speed of formation of an image is increased. Hence, in the device, not only a heating source for a fixing device but also a large number of heating components such as power supplies for drive components such as a motor or a solenoid and for control operations are used. Moreover, since the size of the device is reduced, a large number of complicated components are more densely mounted. Thus, heat is easily left in the device, and the temperature within the device is easily increased. When the temperature within the device is increased, it is likely that toner within a development device is melted and solidified and thus the quality of an image is reduced.
Hence, for example, Japanese Unexamined Patent Application Publication No. 2010-2711 proposes a technology in which a cooling duct is divided into two portions, one cooling duct preferentially cools a process cartridge closest to a heating fixing unit, the other cooling duct cools a process cartridge left by further diving the process cartridge, the temperature difference between the process cartridges is reduced and the entire device is efficiently cooled.
However, in the proposed technology, it is necessary to provide a plurality of cooling ducts and a large blower, and hence the size of the device may be increased. Moreover, in the proposed technology, consideration is not given to the heating of a drive portion for driving the process cartridges. Drive sources such as motors that rotate the photoconductive member of the process cartridge and a development device and a drive transmission mechanism also generate a large amount of heat; it is therefore desirable to provide a cooling structure with consideration given to the heat from these drive sources and the like.
In view of the foregoing conventional problem, the present invention is made; an object of the present invention is to efficiently cool a plurality of image formation portions of an image forming apparatus without the size of the device being increased.